1. Field of the Invention
The present invention relates to a vapor deposition apparatus and a vapor deposition method, and more particularly to a vapor deposition apparatus which is used in a semiconductor manufacturing process or the like and in which occurrence of contaminants is suppressed, and a vapor deposition method for forming a thin film which is uniform in film thickness with little defect.
2. Description of the Related Art
FIG. 3 is a schematic diagram showing a conventional vapor deposition apparatus. In FIG. 3, a rotating substrate holder 32 for mounting a wafer substrate 31 such as silicon wafer or the like, a rotating shaft 33 for rotating the rotating substrate holder 32 and a heater 34 for heating are generally disposed at the lower side in a cylindrical reactor 30, and a motor 35 which is rotationally driven is connected to the rotating shaft 33. Further, plural exhaust ports 36, 36 for exhausting non-reacted gas, etc. are disposed at the bottom portion of the reactor 30, and are connected to an exhaust control device (not shown). Further, plural gas supply pipes 37, 37 and a disc-shaped straightening vane 38 which are adapted to supply raw-material gas and carrier gas into the reactor 30 are provided at the top portion of the reactor 30. Plural holes 38a for regulating the flow of gas are formed in the straightening vane 38. On the side surface of the reactor 30 is provided a wafer substrate feed-in/out port 39 for feeding a wafer substrate (on which a thin film will be vapor-deposited) onto and out from a rotating substrate holder. The wafer substrate feed-in/out port 39 is normally disposed so that the center portion C3 thereof is substantially coincident with the upper surface of the rotating substrate holder 32. For example, the position which is located at a height of about 5 mm to 15 mm from the upper surface of the rotating substrate holder 32 is coincident with the center portion C3 of the wafer substrate feed-in/out port 39.
In the conventional vapor deposition apparatus thus constructed, the substrate 31 mounted on the rotating substrate holder 32 which is rotated at a predetermined rotational number by the rotational driving of the motor 35 is heated to a predetermined temperature by the heater 34 while rotated, and at the same time raw-material gas and carrier gas are supplied into the reactor 30 through the plural gas supply pipes 37, 37 to make uniform the gas momentum and the pressure distribution. Further, these gas are passed through the holes 38a of the straightening vane 38 and then supplied onto the surface of the wafer substrate 31 on the rotating substrate holder 32 at an uniform flow velocity, thereby forming a thin film on the wafer substrate 31 by vapor deposition.
In the vapor deposition apparatus for forming a thin film on a semiconductor wafer, various proposals have been made to prevent occurrence of a lot of particles due to thin-film forming gas and adhesion of deposits to the inner wall of the reactor, and to prevent occurrence of crystal defects due to inconvenience in the thin-film forming process, thereby obtaining a wafer having a thin film which is uniform in quality and thickness. For example, in Japanese Laid-open Patent Application No. Hei-5-74719, the supply amount of raw-material gas is controlled to a predetermined value to prevent the temperature variation in the reactor, thereby preventing occurrence of crystal defects. Further, in Japanese Laid-open Patent Application No. Hei-5-90167, the raw-material gas amount, the pressure in the reactor, the rotational number of the rotating substrate holder, etc. are controlled to predetermined values to prevent slip. In Japanese Laid-open Patent Application No. Hei-6-216045, a part of the inner wall of the reactor on which deposits are liable to be produced is provided with a shielding pipe while the inner peripheral surface thereof is kept smoothened to facilitate a cleaning work of the reactor after the thin-film forming process is finished, and also the gas flow is kept to a laminar flow to form a uniform thin film. Further, in Japanese Laid-open Patent Application No. Hei-7-50260, a method for introducing raw-material gas and carrier gas into the reactor is set to a predetermined one to make the gas momentum and the gas pressure uniform, whereby the raw-material, etc. are supplied at an uniform flow velocity to make the thickness of the thin film uniform.
However, even in the various conventional proposed vapor deposition apparatuses, crystal defects occur in a wafer substrate on which a thin film is grown, and the inconvenience such as adhesion of particles or the like cannot be sufficiently prevented. Further, since higher quality is increasingly required to wafer substrates due to recent ultrahigh integration design of semiconductors, so that degradation of quality due to a slight defect on a thin-film formed wafer substrate frequently induces troubles.